That was supposed to be a deep out but Brees threw the ball a tad early and too short (due to pressure); even the receiver didn't expect the ball to be there.

All i know is that when I watched a coaching video, they prefer the ball to be throw between 35 to 40 yards on such a route.

It's understandable that Jackson looked much higher up in the air if he expected the ball to be thrown deeper (and thefore with a higher trajectory).
But since the ball was thrown short and low, it went below his eyesight.

You do understand that different coaches have different ideas on how things should be done right? You can't watch a couple coaching videos or go to a clinic and deduce how any given team wants to do things.

You are making excuses for Kareem instead of just plainly saying he didn't do a good job there feeling when the ball was coming and locating it.

The part about him expecting one thing and the qb and wr doing something else is hogwash. That's a part if football. This isn't practice. That's not Vance Joseph simulating a qb, and that's not Brice McCain simulating a wr. A football game is not a controlled environment.
Sometimes stuff is going to happen. All the routes and throws aren't going to be exactly where you expect them to be. Part of being a good ball player is reacting in the heat of the moment. If all the balls were thrown where he expected them to be then that would make his job super easy wouldn't it?

Kareem has seemed to have gotten even better on routes in front of him, but he still looks to be lacking when he has to turn his hips, run and defend passes down the field. There is no two ways around that. He needs to continue to improve there.

That's not ragging on him or anything. He's showed tremendous growth, but this is an area if his game that he needs to keep working on. Period.